Secrecy Outage Analysis of Relay-User Pairing for Secure Hybrid Satellite-Terrestrial Networks

• Published in: IEEE transactions on vehicular technology Vol. 71; no. 8; pp. 8906 - 8918
• Main Authors: Cao, Weifeng, Zou, Yulong, Yang, Zhen, Li, Bin, Lin, Yun, Li, Yong, Wu, Wei, Liu, Lizhe
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.08.2022; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Array signal processing; Electronic surveillance; Fading; Hybrid satellite-terrestrial network; Links; Optimization; Outages; physical-layer security; Power system reliability; Probability; Relay; relay-user pairing; Relays; Satellite broadcasting; Satellite communications; Satellites; Security; Signal to noise ratio; Wiretapping
• ISSN: 0018-9545; 1939-9359
• DOI: 10.1109/TVT.2022.3174621

In this paper, we study the physical-layer security of a hybrid satellite-terrestrial network composed of a satellite, multiple terrestrial decode-and-forward (DF) relays and users in the presence of a terrestrial eavesdropper who attempts to tap legitimate information from both satellite and relays. We consider two different scenarios: I) the channel state information (CSI) of wiretap links is known, and II) the CSI of wiretap links is unknown. Accordingly, optimal and suboptimal relay-user pairing schemes are proposed for the aforementioned two scenarios, respectively. Specifically, a relay-user pair maximizing the secrecy rate is chosen as the optimal one to participate in the transmission, where all links' CSI is used to perform relay-user pairing. However, suboptimal relay-user pairing scheme is designed only relying on the main links' CSI without requiring wiretap links' CSI, where a relay-user pair with the maximal transmission rate of main link is selected. Also, closed-form expressions of secrecy outage probability with both integer and rational fading severity parameter are derived in the case of satellite links undergo Shadowed-Rician fading and terrestrial links subject to Rayleigh fading. Furthermore, asymptotic secrecy outage probability analysis is conducted in the high signal-to-noise ratio region. Numerical results reveal that relay-user pairing is beneficial to further improve physical-layer security of the hybrid satellite-terrestrial network.